The present study aims at gaining a better understanding of the cellular and molecular properties of melanoma associated antigens and at developing a microcytotoxic test to detect antibodies to melanoma associated antigens. Efforts will be made to evaluate the expression of histocompatibility antigens and complement components on the membranes of cultured melanoma cells and in sera from melanoma patients. Sera from patients with melanoma and sera from animals immunized with melanoma cells will be examined for the presence of antibodies to melanoma associated antigens. A non-complement dependent test to detect antibodies to melanoma cells will also be evaluated.